The present invention relates to low cost four pole motors and their methods of manufacture, and more particularly, to a new and improved twin bobbin four pole motor as well as new and improved methods of manufacture.
Current four pole motors are typically manufactured as an annular or donut shaped element with four poles equidistantly spaced about the periphery of the annular or donut shaped element. In some designs, a square or rectangular shaped element is chosen in lieu of the annular or donut shaped element. An annular or other closed shape construction is chosen since it produces the shortest magnetic path in the most economical design that can be adapted to a variety of different end uses. For example, the magnetic flux around an annular or donut shaped element is split at each pole in two different paths and comes off each pole in a direction generally perpendicular to the center of each pole. As will be seen in the discussion that follows, such flux path movement while useful in current designs nonetheless creates inherent limitations in improving the cost and operating efficiency of such motors.
In the new and improved twin bobbin four pole construction of the present invention, spaced pairs of legs extend from opposite sides of a four pole central portion which includes a rotor opening for receiving a rotor. At the free end of each of the spaced legs, an end leg extends across to each of such spaced legs. Bobbins are mounted over each leg of the spaced pairs of legs on opposite sides of the central portion or about each of the end legs, depending on the design that is chosen. In either case, substantial savings are possible as a result of the "foot print" of such designs, as well as in the amount of material required for each electrically conductive coil wound about each insulating bobbin. For example, an electrically conductive coil that is positioned over each of the spaced side legs on opposite sides of the central portion can have less than one-half the length of a single electrically conductive coil, in an equivalent magnetic inductor circuit, and the diameter of the electrically conductive wire can be reduced, as well. By positioning an electrically conductive coil on each of the spaced legs, a longer winding length with smaller mean coil winding diameter is provided, resulting in a substantially shorter length for the electrically conductive wire that forms each electrically conductive coil. Additionally, there is a reduction in the diameter of the electrically conductive wire in each such electrically conductive coils. The shorter wire length of each electrically conductive coil is due to the greater surface area of the electrically conductive coils and the proximate location of the spaced electrically conductive coils on the spaced pairs of side legs on each side of the central portion relative to the poles and aligned rotor opening and rotor.
In addition, where insulating bobbins with wound electrically conductive coils are mounted over each pair of stacked legs on opposite sides of the central portion, it may also be possible to provide improved operating performance and efficiency over current four pole motors. In part, this may be due to the greater cross sectional area of the new and improved construction even though the total lamination material used is less.
In certain motor constructions of the present invention, the combined predetermined outer cross sectional configuration of the spaced side legs may have the typical four-sided (square or rectangular) configuration; however, in certain designs, a higher order greater than four sides outer cross sectional shape may be employed in order to produce an even greater savings in the amount of electrically conductive wire required, as compared to typical polygonal cross sectional configurations. This can be further understood by reference to my aforementioned copending patent applications.
In the discussion that follows, the present invention discloses new and improved four pole motor constructions, as well as new and improved methods of manufacturing such motor constructions also with improved efficiency and lower material usage.